In the field of process automation sensors and/or actuators (or effectors, etc.), thus converters (or drive elements, controlling elements), which convert commands of a controller (e.g. of a control computer), mostly present in the form of electrical signals, into forces, movements or other physical effects (such as e.g. a pressure or temperature change), are frequently controlled via point-to-point connections by controllers. An interface component (interface) is frequently arranged between the actual controller and the sensor or actuator, which adapts the electrical properties of the signals emitted by the controller to the properties required for the signals to be received by the sensors or actuators due to the mode of construction and functioning of these sensors or actuators. The controller is located in these cases on the control side of the interface, whereas the side of the interface facing away from the controller is called the field side.
The term “line fault transparency” is understood to be a function of such systems which ensures that a fault, for example a line break or a short circuit, in the wiring on the field side of an interface is transmitted to the control side thereof, so that the controller can detect the fault, and wherein the fault ideally manifests itself on the control side in the same way for the controller as if this fault arising on the field side were present on the control side of the interface. A series of conventional controllers indeed offers the possibility of detecting faults such as line breaks or short circuits in the wiring by field devices connected directly to the controller.
If an interface is switched between the controller and a field device the controller can only detect faults in the cable connection on the control side of the interface but not faults on the field side of the interface. This is particularly problematic in cases in which the interface is arranged in proximity to the controller because the relatively long cable section between the interface and the field device remains unmonitored.